Data centers set up for hot aisle containment enclose hot exhaust air produced by information technology (IT) equipment into contained “hot aisles”. For data centers with row-level cooling systems, this hot exhaust air can be drawn directly into cooling units installed in the cabinet rows, and the airflow may be optimized through modulation of fan speeds within the row-level cooling units. For other cooling scenarios in hot aisle containment systems, the hot exhaust air may be ducted back to the cooling unit(s) via a hot air return plenum. The cooling units of a data center may draw in hot exhaust air from the hot air return plenum, cool the hot exhaust air, and provide the cooled air to the data center.